GB1498824A - Apparatus for monitoring and estimating the loading of an x-ray tube - Google Patents

Abstract

1498824 Monitoring and estimating x-ray tube loading PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 28 Jan 1975 3616/75 Heading G1A Apparatus for this comprises means 1, 4 for providing a first signal representative of the sensed or simulated instantaneous anode temperature T, and means 1, 2, 3 for providing a second signal corresponding to the maximum permissible temperature T max less the predicted increase #T due to energy to be applied in an anticipated exposure, a simulation network 8 providing signal T s representative of accelerated simulation of the variation of anode temperature with time, means for applying the first signal to network 8 at the beginning of its simulation cycle, means 10, 11, 12 for measuring the time between this beginning and when T s becomes less than the second signal, and an indicator 13. Connected to the tube's high voltage supply, circuit 1 gives an output proportional to the power applied to the tube. This is integrated and stored in circuit 2 to give an output proportional to the expected temperature rise #T. The variation of anode temperature is simulated by real time simulator 4, detailed in Fig. 3 (not shown) and its output signal operates a temperature indication 6 and is compared in comparator 5 to operate an alarm if it exceeds T max and in comparator 7 to actuate an exposure blocking device or operate an alarm if it exceeds T max -#T. Simulator 4 can be replaced by a radiation detector and 2 may be replaced by a device multiplying the voltage by the quantity of electricity used. As long as fast simulated signal T s applied to it exceeds T max -#T comparator 9 opens gate 10 so that pulses from generator 11 operate counter 12 and indicator 13 to indicate waiting time. When T s becomes <T max -#T, comparator 9 actuates pulse generator 14 which resets counter 12, blocks 10 and applies a signal to simulator 8 for its cycle to commence. Such cycles are repeated until To <T max -#T, when comparator 7 releases the exposure and blocks generator 14. The fast simulation cycle may be started simply by a push button. The pulses of gate 10 may be integrated and stored and an analogue indication given.